Patch "rtc: m41t80: remove unneeded checks from m41t80_sqw_set_rate" has been added to the 4.14-stable tree

This is a note to let you know that I've just added the patch titled

rtc: m41t80: remove unneeded checks from m41t80_sqw_set_rate

to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:

     rtc-m41t80-remove-unneeded-checks-from-m41t80_sqw_set_rate.patch

and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Troy Kisky <[email protected]>
Date: Thu, 2 Nov 2017 18:58:16 -0700
Subject: rtc: m41t80: remove unneeded checks from m41t80_sqw_set_rate

From: Troy Kisky <[email protected]>

commit 05a03bf260e0480bfc0db91b1fdbc2115e3f193b upstream.

m41t80_sqw_set_rate will be called with the result from m41t80_sqw_round_rate, so might as well make m41t80_sqw_set_rate(n) same as m41t80_sqw_set_rate(m41t80_sqw_round_rate(n))

As Russell King wrote[1],
"clk_round_rate() is supposed to tell you what you end up with if you ask clk_set_rate() to set the exact same value you passed in - but clk_round_rate() won't modify the hardware."

[1]
http://lists.infradead.org/pipermail/linux-arm-kernel/2012-January/080175.html

---
 drivers/rtc/rtc-m41t80.c |   17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

@@ -490,17 +490,12 @@ static int m41t80_sqw_set_rate(struct cl
 		M41T80_REG_WDAY : M41T80_REG_SQW;
 	int reg, ret, val = 0;
 
-	if (rate) {
-		if (!is_power_of_2(rate))
-			return -EINVAL;
-		val = ilog2(rate);
-		if (val == ilog2(M41T80_SQW_MAX_FREQ))
-			val = 1;
-		else if (val < (ilog2(M41T80_SQW_MAX_FREQ) - 1))
-			val = ilog2(M41T80_SQW_MAX_FREQ) - val;
-		else
-			return -EINVAL;
-	}
+	if (rate >= M41T80_SQW_MAX_FREQ)
+		val = 1;
+	else if (rate >= M41T80_SQW_MAX_FREQ / 4)
+		val = 2;
+	else if (rate)
+		val = 15 - ilog2(rate);
 
 	reg = i2c_smbus_read_byte_data(client, reg_sqw);
 	if (reg < 0)

Patches currently in stable-queue which might be from [email protected] are

queue-4.14/rtc-m41t80-m41t80_sqw_set_rate-should-return-0-on-success.patch queue-4.14/rtc-m41t80-avoid-i2c-read-in-m41t80_sqw_is_prepared.patch queue-4.14/rtc-m41t80-avoid-i2c-read-in-m41t80_sqw_recalc_rate.patch queue-4.14/rtc-m41t80-remove-unneeded-checks-from-m41t80_sqw_set_rate.patch queue-4.14/rtc-m41t80-fix-m41t80_sqw_round_rate-return-value.patch